This invention relates generally to a vehicle windshield wiper assembly and specifically to a rocking wiper mechanism for achieving full window clearance.
Vehicle windshield wiper assemblies, which clear rain and other visual obstructions from the windshield glass, are well known in the art. In the automotive industry, vehicle windshield wiper assemblies are considered standard equipment. Almost all automotive vehicles incorporate either a single windshield wiper assembly or a pair of windshield wiper assemblies. Traditionally, a vehicle windshield wiper assembly includes rubber wiper blades mounted on claw brackets, wiper arms attached to the claw brackets and rotating shafts for mounting the wiper arms. It is common in the art to drive the pair of rotating shafts either directly by electric motors or indirectly by a single electric motor that actuates series- or parallel-coupled four-bar linkage mechanisms.
It is also known in the art to employ a window wiper assembly for cleaning rear windows of automotive vehicles. A typical rear window wiper assembly includes a wiper blade mounted on a bracket, a wiper arm coupled to the bracket, a wiper shaft attached to the wiper arm, and a helical gear for rotably driving the wiper shaft in a cyclical oscillating manner. Usually, a reversible, fractional horsepower, direct current electric motor serves to actuate the helical gear through an armature shaft-mounted worm gear enmeshed therewith. A rear window wiper assembly of this type is typically mounted on a pivoting liftgate of a minivan, station wagon, sport-utility vehicle or the like.
Examples of conventional window wiper assemblies and motor mechanisms are disclosed in the following U.S. Pat. No. 5,519,258 entitled "System and Method for Controlling Vehicle Lift Gate Window Wiper" which issued to Stroven et al. on May 21, 1996; U.S. Pat. No. 4,893,039 entitled "Windshield Wiper Motor" which issued to Isii on Jan. 9, 1990; U.S. Pat. No. 4,878,398 entitled "Driving Device for Window Wiper of Motor Vehicles" which issued to Heinrich on Nov. 7, 1989; U.S. Pat. No. 4,336,482 entitled "Rear Window Wiper Motor Control" which issued to Goertler et al. on Jun. 22, 1982; U.S. Pat. No. 4,259,624 entitled "Arrangement for Wiping a Vehicle Window" which issued to Seibicke on Mar. 31, 1981; U.S. Pat. No. 3,694,723 entitled "Motor Vehicle Windshield Wiper Having a Parking Position Outside the Wiper Area" which issued to Schneider et al. on Sep. 26, 1972; and, U.S. Pat. No. 3,665,772 entitled "Windshield Wiper Motor Link Depressed Park Mechanism" which issued to Beard et al. on May 30, 1972.
While it is most favorable to have the maximum area possible cleared on the window, traditional windshield wiper assemblies have failed to achieve full window clearance. Most commonly, vehicle windows are rectangular and the center of rotation of the wiper shaft is below the bottom, or above the top, of the rectangle. The use of this traditional windshield wiper assembly results in portions of the window remaining uncleared due to the attack angle of the blade. This problem is compounded in the liftgate area because the center of rotation of the wiper shaft is typically a more significant distance below the window. When the wipe angle is decreased to smaller values, as in the case of windshield wiper assemblies located in the liftgate area, the uncleared portions of the window become larger.